Introduction
These days are marking the exact anniversary of the earliest direct effects of the Coronavirus disease-2019 (COVID-19) pandemic on the educational sector in the European Union, with Italy as the pioneer member state. In fact, on March 4th, 2020, the Italian government issued a ministerial decree that in its first article declared a nationwide shutdown of pre-schools, schools, and universities, adapting all didactic activities to distance education. By March 20th, when the overall prevalence of COVID-19 in the World Health Organization (WHO) European region was of 151,754 total reported cases (of which 35% were in Italy, 16% in Spain, 14% in Germany and 10% in France), 24 (89%) out of the 27 countries making up the European Union (EU) had fully closed their educational facilities (with Sweden’s schools being partially open and Slovenia’s and Bulgaria’s fully open). Worldwide, on the same date, the United Nations Education, Scientific and Cultural Organization (UNESCO) Global monitoring of school closures caused by COVID-19 reports a total of 146 country-wide closures, affecting 52.4% of total globally enrolled learners. By the end of April 2020, the world had witnessed an unprecedented international disruption of education, with the peak reached on April 26th, 2020, with 82.9% of total enrolled learners affected (equal to a total of 1,451,874,449 learners globally).
As local upsurges of COVID-19 multiplied, so did nationwide lockdowns and concurrent closure of educational facilities. The decision to close schools early in the epidemic outbreak relied partly on data collected from mitigation policies to curb previous pandemics [1] with novel influenza viruses. In the 1918-1919 influenza pandemic, illness rates were highest among children of school age, and mortality rates were highest among infants and young adults other than the elderly [2]. In the 2009 H1N1 virus pandemic children and young adults were once again disproportionately affected [3]. The indications coming from already existing disease modelling studies, rapidly supplemented by new studies published in March-April 2020, evidenced school-closure as a cost-effective non-pharmaceutical intervention for controlling community transmission of seasonal and pandemic influenza viruses [4]. This would be especially noteworthy at a time when documented effective pharmaceutical interventions were unavailable. Although the evidence on the effectiveness of such measures during coronavirus outbreaks were limited, governments acted uniformly in line with the WHO framework for national and local planning and response to the 2009 pandemic , in which proactive rather than reactive school closures/class suspension early in a pandemic outbreak were recommended to achieve the maximal reduction in attack rates. This reduction was expected to be all the greater if framed within the setting of a general lockdown. The likelihood of extra-scholastic student aggregation, which hampers the efficiency of school closures against viral spread, would then be minimized [5].
Nevertheless, due to multiple associated factors, the correlation between school closure and reproduction number (Rt) drop might not be so direct, and such a socially drastic intervention might not always produce an effect of equally drastic magnitude on incidence, hospitalizations and deaths. Already at the time when the global decision to close school was taken, evidence existed to challenge the effectiveness of school closure in the fight against coronaviruses. A scientific evidence-based review published in 2014 concluded that the impact of school closure on the size of the pandemic peak was greatest for viruses whose transmissibility in the community was low (i.e. with a basic Rt <2) and whose attack rates were higher in children than in adults [6]. Neither of these two conditions appeared to be applicable to Sars-Cov-2 at the start of the outbreak. However, evidence also existed in a second systematic review from 2018 that school closure could prove to be a measure on its own to control infectious spread, not merely a bridge until other measures are found [1].
In the short and medium term, immediate COVID-19 containment was prioritized over optimal educational continuity and the combined deployment of all readily amenable interventions did manage to curtail the first outbreak within the WHO European Region. By May 31st, 2020, incidence and case-fatality ratio decreased, with 717 deaths out of the 19,995 daily cases as reported to the WHO compared to the 5,312 daily deaths out of 41,265 daily cases, which corresponded to the peak of the first wave (registered for the WHO European region on April 4th, 2020). However, the steadiness of epidemiological parameters between spring and autumn term, when schools re-opened in most of Europe, represented only a temporary hiatus, and a second outbreak started. Although currently the outlook on the pandemic is still narrow, as new empirical evidence on the severe acute respiratory syndrome coronavirus 2 (Sars-Cov-2) and its variants grow on a daily basis, cumulative ongoing research has completely changed the context in which outbreaks are occurring, gradually diminishing key unknowns about the virus transmissibility, target populations, case-fatality, clinical features and available pharmacological interventions. Mass vaccinations that are occurring worldwide, and the chronicization of the COVID-19 pandemic, causes a paradigm shift for paediatricians and whoever else operates in the field of health promotion for children and adolescents. When considering only the younger demographic groups, the major problem related to the pandemic increasingly appears not to be the emergent infectious disease itself but its long-lasting pervasive indirect consequences. It is our responsibility to remain updated on both direct and indirect health effects of COVID-19 on our patient population.
The present literature review will focus on only one such indirect health effect of the pandemic: the prolonged early school closures and their precarious re-opening. Early decision-making surrounding educational facilities across the globe relied on multiple assumptions and could claim as its main objectives the protection of children, of educational staff and of the community as a whole from uncontrolled spread of COVID-19, employing a cost-effective policy. Our aim is to understand which, if any, of the original assumptions is now fact-based, and whether the multifaceted latest knowledge on COVID-19 and its epidemiology in children is accounted for by policymakers, in a world that has currently lost on average 22 weeks of normal education (UNESCO data updated to January 25th), and up to more than 50 weeks in some countries (India, USA, Brazil, to cite a few). The large existing differences in the re-opening policies among different countries and in the published study types represent an informative starting point, lessening the risk of both collinearity bias and population bias compared to literature reviews compiled during the first wave of the pandemic. School closures were initially used in combination with multiple other mitigation strategies and testing, as well as medical care, prioritized symptomatic populations, i.e. including older adults more frequently than children.
References for this review were initially identified through searches of PubMed, Scopus and Cochrane Library for articles published from March, 2020, to March, 2021 by use of the terms “Schools” “COVID-19” “pandemic” “clusters” “outbreak” “seroprevalence”. Further search was undertaken through Google Scholar and ResearchGate, and finally through Google. Articles published in English resulting from these searches and relevant references cited by those articles were then reviewed.